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Author Topic: I ordered an MT644 and I received an MT647  (Read 1693 times)
Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« on: May 27, 2014, 07:17:50 AM »

What is the difference between transmissions? I have some information but can't figure out the difference. Obviously they are in the same family and have similar torque and horsepower input limitations.

Thanks, Fred
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Fred Thomson
luvrbus
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« Reply #1 on: May 27, 2014, 07:28:18 AM »

Houston you may have a problem the 647 is almost 6 inches longer and  some are electronic controlled unless Bobby changed the valve body  or is that the 653 that is longer I will check on it for you but measure it anything over 31 inches won't work for you

good luck
« Last Edit: May 27, 2014, 07:40:33 AM by luvrbus » Logged

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Lin
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« Reply #2 on: May 27, 2014, 09:18:37 AM »

We have the 647 in our 5a.  It is definitely not electronic.  I have not checked anything, but I do not think it is longer than the 644.  As I remember it, the 647 had some internal durability upgrades from the 644.
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TomC
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« Reply #3 on: May 27, 2014, 09:23:13 AM »

Lin is correct-the MT647 is a MT643, MT644, etc with the most upgrades. Still a 4spd and the shorter transmission compared to the 5spd. As long as it is a mechanical trans, you'll be fine. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #4 on: May 27, 2014, 11:27:38 AM »

OK Thanks guys. They say the only way to install the bolts that go through the flexplate into the torque converter is to remove a plug in the rear case and reach through that opening with the extension socket. Haven't had a chance to look but I wonder if I could reach those bolt locations through the starter opening.

Should I loctite those bolts? If so, which color should I use? What is the torque specification for those bolts?


Fred
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Fred Thomson
bevans6
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« Reply #5 on: May 27, 2014, 11:35:11 AM »

Dang, that looks nice!  Would you care to PM me the ballpark cost for the package?  It looks very complete.  Do you need an adaptor ring or different rear housing on the 8V-71?

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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luvrbus
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« Reply #6 on: May 27, 2014, 12:52:42 PM »

Torque the flywheel to the engine @ 180 to 190 ft lbs look above the starter there is a plug to remove to get to the plate to bolt up the transmission. 

I don't see any ATEC crap on the transmission and I checked it is 30-1/2 long. I got into a 647 that had a electronic park before man was that a night mare it was a off road 647 it was a strange duck indeed 
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Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #7 on: May 27, 2014, 02:32:30 PM »

Brian,
THere is an SAE1 to SAE2 Bell Housing Adapter on there. Here is another view where you can see the silver ring. There is also an adapter from the 8V71 crankshaft to the torque converter but I don't have it yet. THere aren't many of them in existence anymore and mine got lost in the mail apparently. Yes it is a very complete kit, even came with a dipstick and tube and an air to oil cooler. A manual modulator and cooling line fittings. Transmission is a running take out that was dyno'd and has a new filter installed.

I did not have a core so the total bill came to around $5,900.00. It would have been about $10,000.00 installed. A lot of money but the bus is worthless with the manual transmission and I really needed another project to go with the hole in my head............



Fred
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Fred Thomson
bevans6
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« Reply #8 on: May 27, 2014, 02:48:37 PM »

Thank you!  I am amazed at how much smaller it looks than the 8844.  Tighter and tidier.  Good deal, it should be wonderful.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
lvmci
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« Reply #9 on: May 27, 2014, 05:26:29 PM »

Hi Fred, my MT643 is set for a max of 250 horsepower I think, were the updated MTs higher horse capable? Lvmci...
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MCI5A 8V71 Allison MT643
Ed Hackenbruch
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« Reply #10 on: May 27, 2014, 06:24:34 PM »

My 644 is rated for 300 hp.
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
luvrbus
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« Reply #11 on: May 27, 2014, 07:12:26 PM »

The 647 is rated for 300 hp also but the torque rating is 950 # it will standup behind the 6V92 325hp the 644 has torque rating of 780 # with 300 hp,the 643 is only rated at 640# of torque with 250 hp but can be used on a 4000 rpm engine where the others cannot be used over 3000 rpm
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TomC
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« Reply #12 on: May 28, 2014, 08:44:27 AM »

Since you have both the engine and transmission out, this would be the perfect time to add a turbocharger. By keeping the N65 injectors, you'll boost the engine from 300hp and 800lb/ft torque to 325hp and 975lb/ft torque. It is a bit over the transmissions advertised capability, but, like me, you're typically not driving the bus with your foot on the floor like a commercial bus driver would be. The most noticeable change will be no performance loss at higher altitude. And with just keeping the same injectors, you can keep the turbo boost under 10psi so not to create a lot of heat.

The V730 is rated at 275hp and 780lb/ft torque. Yet I'm pushing 375hp at 1125lb/ft torque through mine with no problem. Course, I had the trans rebuilt and they also increased the oil pressure. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #13 on: June 04, 2014, 07:30:22 PM »

Oh Boy having a heck of a time getting the correct adaptions for this combination. Need to put a crankshaft hub adapter on to mount the flexplate. The flexplate has the starter gear on it with an MT647. So I got that right, but now am having problems finding a SAE 1 bell housing adapter that is the right length. Looks like I need 1.500" and a step down from SAE 1 to SAE 2 because the tranny is SAE2. Might be able to find a step down adapter that is 1.500" here in town hopefully.

Then I'll need to shorten the driveshaft. And I'm being told I may need to shim the engine up an inch to help line up the new shorter drive shaft. The project seems simple enough, but it's not.

Does anyone know if I'm going to need to shim that engine after I get the driveshaft shortened? The engine is so tight in the MC-5 that I can't imagine shimming the transmission end. Maybe the fuel pump end?
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Fred Thomson
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« Reply #14 on: June 04, 2014, 08:19:05 PM »

Unbelievable Fred they knew you needed the spacer Kim sent me a blank and I had to have the holes drilled been a long time ago but I was thinking it was 15/16 If I had a SAE 2 bell housing I would ship it to you and you would be done I lowered the front of my engine with different mounts not by much isn't the drive shaft 13 inches ?
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Lin
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« Reply #15 on: June 04, 2014, 10:22:23 PM »

Sorry, I did not read this until after I sent you an email, so I guess there is a little duplication.  Wasn't the kit supposed to include everything?
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Fredward
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« Reply #16 on: June 05, 2014, 04:02:24 AM »

Yes the kit was supposed to include everything but it's been so long since  they've done one that they don't have all the details anymore.

Clifford when you say lower the front of the engine, do you mean the transmission end of the engine or the fuel pump end. On the transmission end there is only about 3/4" rubber mounts there to start with. 


Fred
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Fred Thomson
bevans6
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« Reply #17 on: June 05, 2014, 04:36:20 AM »

I think you will have to lower the front of the engine, which is to say the part that doesn't have the transmission bolted to it...  To get an angle to raise the output flange of the transmission to get it to line up a bit better with the input on the drop box.  You'll have to cut and weld the front engine mount to do that. 

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Lin
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« Reply #18 on: June 05, 2014, 10:08:12 AM »

I don't remember exactly what Don did to mine, but I don't think he had to remake the supports.  Try calling him.  Sam Caylor would probably also know, and may have any further parts you need.

Just for encouragement.  When your all done, you will think it was worth the trouble.
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Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #19 on: June 05, 2014, 04:19:08 PM »

Havn't reached Don yet. Sam said definitely raise the transmission end 3/4" with shims. I can't raise it much more than that or the compressor or air intake snout will hit the floor above. I have a driveline alignment calculator that I'll try once I get the transmission attached and everything shoved back in the bus. RIght now I'm still working on the bell housing adapter thickness. Looks like I'll have to buy a #2 - #2 adapter about .900" and have it machined down to about .550" or .600.".


Fred
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Fred Thomson
luvrbus
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« Reply #20 on: June 05, 2014, 04:59:23 PM »

That one I do not agree with Sam you drop the front a 1/4 of a inch the angle changes big time in 70 inches Eagle has always dropped the front of their engines to achieve the angle for the drop box with a 644 or 740, just put a level on a 8v71 in a Eagle and you will see what I am saying 

You can buy a electronic angle and level at HD,Lowes or Amazon for 50 bucks you stay with the Spicier specs it will work

good luck
« Last Edit: June 05, 2014, 05:39:09 PM by luvrbus » Logged

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Lin
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« Reply #21 on: June 05, 2014, 07:13:47 PM »

Mine did put the compressor up against the top of the engine compartment.  Since it was at the under bed storage compartment, Don cut a hole there, and I built a box to go over the hole that now also serves as an access panel to the area.
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Fredward
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MC-5A #5401 8" roof raise 8V71 with MT647




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« Reply #22 on: June 06, 2014, 03:50:29 AM »

Well that's interesting. When Don called me back he said he didn't recall shimming the engine. But from what you say he must have determined that it is necessary to shim it. I will call him again and ask.

The guys I'm talking to at Dartco sent me a driveline angle calculator spreadsheet to help identify the need or lack thereof.


Fred
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Fred Thomson
Lin
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« Reply #23 on: June 06, 2014, 03:22:43 PM »

I seem to remember that we had to resize the fan belt due to tilting the engine too.
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Fredward
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« Reply #24 on: June 09, 2014, 04:20:47 AM »

Well I guess we will learn the extent of required modifications soon. I'll get the bell housing adapter Tuesday. 


Fred
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